U.S. patent application number 11/382366 was filed with the patent office on 2006-11-30 for hard-coated member.
This patent application is currently assigned to HITACHI TOOL ENGINEERING, LTD.. Invention is credited to Takeshi Ishikawa.
Application Number | 20060269788 11/382366 |
Document ID | / |
Family ID | 36617299 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060269788 |
Kind Code |
A1 |
Ishikawa; Takeshi |
November 30, 2006 |
HARD-COATED MEMBER
Abstract
A hard-coated member comprising a hard coating comprising a
lowermost layer, an intermediate laminate and an uppermost layer on
a substrate, the intermediate laminate being constituted by
alternately laminated layers A and layers B having different
compositions, the layers A and the layers B being respectively made
of at least one selected from the group consisting of nitrides,
borides, carbides and oxides of metal components having
compositions represented by the formula of
Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W, X, Y and Z
respectively represent atomic % of Al, Cr, Ti and Si, W+X+Y+Z=100,
and these combinations, the layers A meeting the condition of
70.ltoreq.W+X<100, the layers B meeting the condition of
30.ltoreq.Y<100, and the uppermost layer being made of at least
one selected from the group consisting of nitrides, carbides,
sulfides and borides of Ti or Ti and Si and these combinations, or
at least one selected from the group consisting of nitrides,
carbides, sulfides and borides of Cr or Cr and Si and these
combinations.
Inventors: |
Ishikawa; Takeshi;
(Chiba-ken, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
HITACHI TOOL ENGINEERING,
LTD.
|
Family ID: |
36617299 |
Appl. No.: |
11/382366 |
Filed: |
May 9, 2006 |
Current U.S.
Class: |
428/698 ;
428/701; 428/702 |
Current CPC
Class: |
C23C 14/0623 20130101;
C23C 14/325 20130101; C23C 28/04 20130101; Y10T 428/24942 20150115;
C23C 14/0676 20130101; C23C 14/06 20130101; C23C 30/005 20130101;
C23C 14/0641 20130101; C23C 14/0664 20130101; C23C 14/3492
20130101 |
Class at
Publication: |
428/698 ;
428/701; 428/702 |
International
Class: |
B32B 9/00 20060101
B32B009/00; B32B 19/00 20060101 B32B019/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 26, 2005 |
JP |
2005-153630 |
Nov 16, 2005 |
JP |
2005-331192 |
Nov 16, 2005 |
JP |
2005-331193 |
Claims
1. A hard-coated member comprising a hard coating comprising a
lowermost layer, an intermediate laminate and an uppermost layer on
a substrate member, said intermediate laminate being constituted by
alternately laminated layers A and layers B having different
compositions, said layers A and said layers B being respectively
made of at least one selected from the group consisting of
nitrides, borides, carbides and oxides of metal components having
compositions represented by the formula of
Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W, X, Y and Z
respectively represent atomic % of Al, Cr, Ti and Si, W+X+Y+Z=100,
and these combinations, said layers A meeting the condition of
70.ltoreq.W+X<100, said layers B meeting the condition of
30.ltoreq.Y<100, and said uppermost layer being made of at least
one selected from the group consisting of nitrides, carbides,
sulfides and borides of Ti or Ti and Si and these combinations.
2. A hard-coated member comprising a hard coating comprising a
lowermost layer, an intermediate laminate and an uppermost layer on
a substrate, said intermediate laminate being constituted by
alternately laminated layers A and layers B having different
compositions, said layers A and said layers B being respectively
made of at least one selected from the group consisting of
nitrides, borides, carbides and oxides of metal components having
compositions represented by the formula of
Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W, X, Y and Z
respectively represent atomic % of Al, Cr, Ti and Si, W+X+Y+Z=100,
and these combinations, said layers A meeting the condition of
70.ltoreq.W+X<100, said layers B meeting the condition of
30.ltoreq.Y<100, and said uppermost layer being made of at least
one selected from the group consisting of nitrides, carbides,
sulfides and borides of Cr or Cr and Si and these combinations.
3. The hard-coated member according to claim 1, wherein said
uppermost layer is based on a carbonitride, a sulfide or a boride
containing 50 atomic % or more of Ti.
4. The hard-coated member according to claim 2, wherein said
uppermost layer is based on a carbonitride, a sulfide or a boride
containing 50 atomic % or more of Cr.
5. The hard-coated member according to any one of claim 1, wherein
said layers A and said layers B in said intermediate laminate are
respectively as thick as 0.5-100 nm.
6. The hard-coated member according to any one of claim 1, wherein
said intermediate laminate has at least two peaks in X-ray
diffraction in a 2.theta. range of 40.degree. to 45.degree..
7. The hard-coated member according to any one of claim 1, wherein
at least Al, Cr and Ti are mutually diffused in said layers A and
said layers B constituting said intermediate laminate.
8. The hard-coated member according to any one of claim 1, wherein
the layer in said intermediate laminate has higher Si concentration
as it nears the surface.
9. The hard-coated member according to any one of claim 1, wherein
said lowermost layer is made of a nitride comprising at least one
metal element selected from the group consisting of Al, Cr, Ti and
Si.
10. The hard-coated member according to any one of claim 1, wherein
there is mutual diffusion in interfaces between said lowermost
layer and said intermediate laminate, between the layer A and the
layer B in said intermediate laminate, and between said uppermost
layer and said intermediate laminate.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a hard-coated member having
not only excellent lubrication and resistance to peeling from a
substrate, but also excellent seizure resistance and/or wear
resistance, which is suitable as members requiring high hardness,
such as cutting tools, molding dies, bearings, forming dies, rolls,
etc.
BACKGROUND OF THE INVENTION
[0002] Cutting tools, etc. are provided with single- or multi-layer
hard coatings made of carbides, nitrides and carbonitrides of Al,
Cr, Ti and Si, or oxides of Al, etc., to improve hardness, wear
resistance, lubrication, seizure resistance, etc. Particularly
because coatings of composite nitrides of Ti and Al (TiAlN) exhibit
excellent wear resistance, they are formed on cutting tools of
high-hardness materials such as high-speed steel, hardened steel,
etc.
[0003] JP 2003-71610A discloses a cutting tool having a multi-layer
coating, as a hard coating having higher wear resistance than
TiAlN, which is formed by alternately laminating two types of
layers having different compositions plurality times, both within a
composition range represented by
(Ti.sub.aAl.sub.bCr.sub.c)(C.sub.1-dN.sub.d), wherein a, b and c
represent the atomic ratios of Ti, Al and Cr, respectively, and d
represents the atomic ratio of N, meeting
0.02.ltoreq.a.ltoreq.0.30, 0.55.ltoreq.b.ltoreq.0.765,
0.06.ltoreq.c,a+b+c=1, and 0.5.ltoreq.d.ltoreq.1, or
0.02.ltoreq.a.ltoreq.0.175, 0.765.ltoreq.b, 4(b-0.75).ltoreq.c,
a+b+c=1, and 0.5.ltoreq.d.ltoreq.1. Although this multi-layer
coating has excellent wear resistance, it falls to sufficiently
meet an increasingly mounting demand to provide cutting tools with
higher wear resistance and/or seizure resistance.
[0004] JP 2004-238736A discloses a hard coating formed by an
arc-discharge ion plating method, which has a composition
comprising a metal component represented by Al.sub.xCr.sub.1-x
wherein x represents an atomic ratio meeting
0.45.ltoreq.x.ltoreq.0.75, and a non-metal component represented by
N.sub.1-.alpha.-.beta.-.gamma.B.sub..alpha.C.sub..beta.O.sub..gamma.,
wherein .alpha., .beta. and .gamma. respectively represent atomic
ratios meeting 0 .ltoreq..alpha..ltoreq.0.15,
0.ltoreq..beta..ltoreq.0.35, and 0.01.ltoreq..gamma..ltoreq.0.25,
the hard coating having the maximum X-ray diffraction intensity in
a (200) plane or a (111) plane, and the bonding energy of Al and/or
Cr and oxygen in a range of 525-535 eV in X-ray electron
spectroscopy. It further describes that a hard coating formed by
laminating two layers having different compositions within the
above ranges has not only improved hardness and wear resistance,
but also improved adhesion to a substrate. However, it still falls
to sufficiently meet an increasingly mounting demand to provide
cutting tools with higher wear resistance and/or seizure
resistance.
[0005] JP 7-205361A discloses a member having a hard coating formed
by laminating at least one compound selected from the group
consisting of nitrides, oxides, carbides, carbonitrides and borides
of metal elements of Groups IVa, Va and VIa, Al and Si, and a
nitride, an oxide, a carbide, a carbonitride and/or a boride of two
types of metal elements selected from the group consisting of metal
elements of Groups IVa, Va and VIa, Al and Si, at a period of
0.4-50 nm to a total thickness of 0.5-10 .mu.m. Although this hard
coating has excellent wear resistance, it still fails to
sufficiently meet an increasingly mounting demand to provide
cutting tools with higher wear resistance and/or seizure
resistance.
OBJECT OF THE INVENTION
[0006] Accordingly, an object of the present invention is to
provide a hard-coated member having not only excellent lubrication
and resistance to peeling from a substrate, but also excellent
seizure resistance and/or wear resistance.
DISCLOSURE OF THE INVENTION
[0007] As a result of intensive research in view of the above
object, it has been found that by forming an upper layer made of at
least one of nitrides, carbides, sulfides and borides of Ti or Ti
and Si, or at least one of nitrides, carbides, sulfides and borides
of Cr or Cr and Si on a laminate having two types of layers having
different compositions, it is possible to obtain a hard coating
having not only excellent lubrication and resistance to peeling
from a substrate, but also excellent seizure resistance and/or wear
resistance. The present invention has been completed based on such
finding.
[0008] Thus, the first hard-coated member of the present invention
comprises a hard coating comprising a lowermost layer, an
intermediate laminate and an uppermost layer on a substrate, the
intermediate laminate being constituted by alternately laminated
layers A and layers B having different compositions, the layers A
and the layers B being respectively made of at least one selected
from the group consisting of nitrides, borides, carbides and oxides
of metal components having compositions represented by the formula
of Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W, X, Y and Z
respectively represent atomic % of Al, Cr, Ti and Si, W+X+Y+Z=100,
and these combinations, the layers A meeting the condition of
70.ltoreq.W+X<100, the layers B meeting the condition of
30.ltoreq.Y<100, and the uppermost layer being made of at least
one selected from the group consisting of nitrides, carbides,
sulfides and borides of Ti or Ti and Si and these combinations.
[0009] The second hard-coated member of the present invention
comprises a hard coating comprising a lowermost layer, an
intermediate laminate and an uppermost layer on a substrate, the
intermediate laminate being constituted by alternately laminated
layers A and layers B having different compositions, the layers A
and the layers B being respectively made of at least one selected
from the group consisting of nitrides, borides, carbides and oxides
of metal components having compositions represented by the formula
of Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W, X, Y and Z
respectively represent atomic % of Al, Cr, Ti and Si, W+X+Y+Z=100,
and these combinations, the layers A meeting the condition of
70.ltoreq.W+X<100, the layers B meeting the condition of
30.ltoreq.Y<100, and the uppermost layer being made of at least
one selected from the group consisting of nitrides, carbides,
sulfides and borides of Cr or Cr and Si and these combinations.
[0010] In the first hard-coated member, the uppermost layer is
preferably based on a carbonitride, a sulfide or a boride
containing 50 atomic % or more of Ti.
[0011] In the second hard-coated member, the uppermost layer is
preferably based on a carbonitride, a sulfide or a boride
containing 50 atomic % or more of Cr.
[0012] The layers A and the layers B in the intermediate laminate
are preferably as thick as 0.5-100 nm.
[0013] The intermediate laminate preferably has at least two peaks
in X-ray diffraction in a 2.theta. range of 40.degree. to
45.degree..
[0014] In the layers A and the layers B constituting the
intermediate laminate, at least Al, Cr and Ti are mutually
diffused.
[0015] The layer in the intermediate laminate preferably has higher
Si concentration as it nears the surface.
[0016] The lowermost layer is preferably made of a nitride
comprising at least one metal element selected from the group
consisting of Al, Cr, Ti and Si.
[0017] There is preferably mutual diffusion in interfaces between
the lowermost layer and the intermediate laminate, between the
layer A and the layer B in the intermediate laminate, and between
the uppermost layer and the intermediate laminate.
DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic cross-sectional view showing the layer
structure of a hard coating in the hard-coated member of the
present invention.
[0019] FIG. 2 is a schematic view showing one example of an
apparatus for forming the hard coating.
[0020] FIG. 3 is a graph showing an X-ray diffraction pattern of
the intermediate laminate of Sample 1.
[0021] FIG. 4 is a STEM photograph showing part of the intermediate
laminate and the uppermost layer of Sample 1.
[0022] FIG. 5 is a photograph showing a selected-area diffraction
image of the intermediate laminate of Sample 1.
[0023] FIG. 6 is a photograph obtained by enlarging the STEM
photograph of FIG. 4.
[0024] FIG. 7 is a schematic view showing another example of an
apparatus for forming the hard coating.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] [1] Layer Structure of Hard Coating
[0026] As shown in FIG. 1, the hard-coated member of the present
invention has a structure comprising a hard coating comprising a
lowermost layer, an intermediate laminate and an uppermost layer on
a substrate. The intermediate laminate has a structure comprising
alternately laminated layers A and layers B having different
compositions. It is preferable that these layers are continuously
laminated on a substrate surface by a physical vapor deposition
method.
[0027] The uppermost layer functions to improve not only hardness,
heat resistance, lubrication, etc., but also seizure resistance
and/or wear resistance. The lowermost layer absorbs the residual
stress of the intermediate laminate and the uppermost layer,
prevents peeling and abnormal wear, and improves wear resistance.
The intermediate laminate assists the uppermost layer to exhibit
its properties sufficiently.
[0028] (1) Composition of Uppermost Layer
[0029] The uppermost layer has a different composition from that of
the intermediate laminate. The first hard-coated member has an
uppermost layer based on a carbonitride, a sulfide or a boride
containing 50 atomic % or more of Ti (hereinafter referred to
simply as "first uppermost layer"), and the second hard-coated
member has an uppermost layer based on a carbonitride, a sulfide or
a boride containing 50 atomic % or more of Cr (hereinafter referred
to simply as "second uppermost layer").
[0030] Any uppermost layer is preferably as thick as 50 nm or more
to obtain the above effect. The uppermost layer preferably contains
oxygen such that the concentration of oxygen is highest in a depth
range within 100 nm. The inclusion of oxygen is particularly
effective to prevent the seizure of a work material to a hard
coating surface. Incidentally, another layer may be formed on the
uppermost layer. For instance, because the uppermost layer of the
present invention is so grayish that it is difficult to discern by
the naked eye whether or not the coating is formed, a dark-color
layer such as a carbon layer, etc. may be formed on the uppermost
layer to identify the presence of the hard coating.
[0031] (a) Composition of First Uppermost Layer
[0032] The first uppermost layer is made of at least one selected
from the group consisting of nitrides, carbides, sulfides and
borides of Ti or Ti and Si and these combinations, and may contain
several % of other inevitably introduced elements. The first
uppermost layer is preferably a layer based on a carbonitride, a
sulfide or a boride containing 50 atomic % or more of Ti. In an
interface between the first uppermost layer and the intermediate
laminate, their compositions are preferably mutually diffused to
improve adhesion strength. The first uppermost layer provides the
coating with improved hardness. It further extremely suppresses
peeling and abnormal wear, and improves the lubrication of the
entire hard coating, resulting in extreme improvement in chip
dischargeability. The first uppermost layer is particularly
suitable as coating layers for drills.
[0033] (b) Composition of Second Uppermost Layer
[0034] The second uppermost layer is made of at least one selected
from the group consisting of nitrides, carbides, sulfides and
borides of Cr or Cr and Si, and these combinations, and may contain
several % of other inevitably introduced elements. The second
uppermost layer is preferably a layer based on a carbonitride, a
sulfide or a boride containing 50 atomic % or more of Cr. In an
interface between the second uppermost layer and the intermediate
laminate, their compositions are preferably mutually diffused to
improve adhesion strength. The second uppermost layer improves
lubrication and seizure resistance while maintaining good heat
resistance and wear resistance. It further extremely suppresses
peeling and abnormal wear, and improves the lubrication of the
entire hard coating, resulting in extreme improvement in chip
dischargeability. The second uppermost layer is particularly
suitable as coating layers for drills and end mills.
[0035] (2) Composition of Intermediate Laminate
[0036] The intermediate laminate has a structure comprising
alternately laminated layers A and layers B having different
compositions, and any of the layers A and the layers B is made of
at least one selected from the group consisting of nitrides,
borides, carbides and oxides of metal components having
compositions represented by the formula of
Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W, X, Y and Z
respectively represent atomic % of Al, Cr, Ti and Si, W+X+Y+Z=100,
and these combinations.
[0037] The metal component of the layer A has a composition of
Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein W+X+Y+Z=100, and
70.ltoreq.W+X<100 (atomic %). When the value of (W+X) is less
than 70, the layers A are insufficient not only in a heat
resistance-improving effect, but also in hardening by combination
of the layers B. Incidentally, even the slightest amount of Si
contributes to improvement in the hardness of the layers A. On the
premise of meeting the condition of 70.ltoreq.W+X<100, W meets
preferably 30.ltoreq.W.ltoreq.70, more preferably
35.ltoreq.W.ltoreq.70, particularly 45.ltoreq.W.ltoreq.65. Also, X
meets preferably 20.ltoreq.X.ltoreq.60, more preferably
25.ltoreq.X.ltoreq.50, particularly 25.ltoreq.X.ltoreq.35. Y and Z
meet preferably 0<Y.ltoreq.30 and Z.ltoreq.10, more preferably
2.ltoreq.Y.ltoreq.10 and Z.ltoreq.5.
[0038] The metal component in the layers B has a composition
represented by Al.sub.WCr.sub.XTi.sub.YSi.sub.Z, wherein
W+X+Y+Z=100, and 30.ltoreq.Y.ltoreq.100 (atomic %). When the value
of Y is less than 30, the layers A have low adhesion strength to
the layers B, resulting in the intermediate laminate with
insufficient hardness. This is due to the fact that the crystal
structure of the intermediate laminate has an hcp structure.
Incidentally, even the slightest amount of Si contributes to
improvement in the hardness of the layers B. Y meets preferably
30.ltoreq.Y.ltoreq.95, more preferably 30.ltoreq.Y.ltoreq.90. W, X
and Z meet preferably 0<W.ltoreq.50, 0<X.ltoreq.20, and
Z.ltoreq.20, more preferably 1.ltoreq.W.ltoreq.50,
1.ltoreq.X.ltoreq.15, and Z.ltoreq.10.
[0039] The thickness of each layer A, B is preferably 0.5-100 nm,
more preferably 1-70 nm, particularly 2-50 nm. With such thickness,
the intermediate laminate containing Al, Cr and Ti as indispensable
components is provided with high hardness, resulting in improvement
in its adhesion strength to the lowermost layer and the uppermost
layer, and the strength balance of the entire hard coating. When
each layer A, B has a thickness of less than 0.5 nm, it has low
hardness and lubrication. On the other hand, when each layer A, B
has a thickness of more than 100 nm, the intermediate laminate does
not have sufficiently high hardness. Incidentally, even if the
intermediate laminate has other layers as thick as 100 nm or more
in addition to the layers A and the layers B, the intermediate
laminate can exhibit the above properties.
[0040] The intermediate laminate preferably has at least two peaks
in X-ray diffraction in a 2.theta. range of 40.degree. to
45.degree.. This means that 2 or more other phases having different
lattice constants are formed in the intermediate laminate, thereby
inducing strain in the intermediate laminate, and thus contributing
to increasing the hardness.
[0041] The layers A and the layers B constituting the intermediate
laminate are preferably layers in which at least Al, Cr and Ti are
mutually diffused. The mutual diffusion improves adhesion strength
in interfaces between the lowermost layer and the intermediate
laminate, between the layers A and the layers B in the intermediate
laminate, and between the intermediate laminate and the uppermost
layer, resulting in providing the intermediate laminate with
improved hardness, and providing the entire hard coating with
optimized strength balance. The presence of mutually diffused
layers can be confirmed by lattice image observation by a
transmission electron microscope, and the energy-dispersive X-ray
spectroscopy (EDS) analysis of each layer.
[0042] A crystal lattice is preferably continuous between the
layers A and the layers B, to improve the adhesion strength of the
layers A to the layers B and their wear resistance. The continuous
crystal lattice structure can be confirmed by lattice image
observation by a transmission electron microscope, a selected-area
diffraction image, or a micro-area electron beam diffraction.
[0043] The Si content in the intermediate laminate preferably
increases as the layer nears the surface. This provides the
intermediate laminate with adhesion strength, hardness and strength
changing in a thickness direction, thereby improving the wear
resistance of the entire hard coating.
[0044] (3) Composition of Lowermost Layer
[0045] The lowermost layer is preferably made of at least one metal
element selected from the group consisting of nitrides of Al, Cr,
Ti and Si. The lowermost layer preferably contains 50 atomic % or
more of Al. The lowermost layer having such composition relaxes the
stress of the intermediate laminate and the uppermost layer. There
is preferably mutual diffusion in an interface between the
lowermost layer and the intermediate laminate. The mutual diffusion
improves the adhesion strength. It may contain a trace amount of
oxygen, carbon, boron or sulfur as a non-metal component other than
nitrogen.
[0046] The compositions of the uppermost layer, the intermediate
laminate and the lowermost layer can be analyzed by an electron
probe microanalyzer (EPMA), an energy-dispersive X-ray spectroscope
(EDX), EDS attached to a transmission electron microscope, or an
electron energy loss spectroscope (EELS). For the composition
analysis of each layer, analyses such as a Rutherford
backscattering spectrometory (RBS), an electron spectroscopy (XPS),
AES, etc. may also be used.
[0047] (4) Thickness and Properties of Each Layer
[0048] (a) Thickness of Each Layer
[0049] The thickness T.sub.U of the uppermost layer is preferably
0.01-5 .mu.m. When the uppermost layer is less than 0.01 .mu.m, it
provides insufficient effects of improving seizure resistance
and/or wear resistance. On the other hand, when the uppermost layer
is more than 5 .mu.m, a sufficient wear resistance-improving effect
cannot be obtained. The thickness T.sub.M of the intermediate
laminate is preferably 0.1-5 .mu.m. When the intermediate laminate
is less than 0.1 .mu.m, well-balanced adhesion strength, hardness
and strength are not achieved between the uppermost layer and the
lowermost layer, failing to sufficiently improve the wear
resistance. The thickness T.sub.L of the lowermost layer is
preferably 0.01-3 .mu.m. When the lowermost layer is less than 0.01
.mu.m, it falls to cause the high hardness of the uppermost layer
to sufficiently improve the wear resistance. On the other hand,
when the thickness of the lowermost layer is more than 3 .mu.m, the
hard coating is likely to peel off or be abnormally worn.
Particularly when the relation of
T.sub.M.gtoreq.T.sub.U.gtoreq.T.sub.L is met, the effect of the
present invention can be exhibited at maximum.
[0050] (b) Properties
[0051] The hardness H of the intermediate laminate is preferably
30-50 GPa, more preferably 30-40 GPa. The modulus E of the
intermediate laminate is preferably 450-550 GPa. The modulus
recovery ratio R of the intermediate laminate is preferably 28-38%,
more preferably 28-34%. When the value of R is less than 28%, the
hard coating has insufficient wear resistance. On the other hand,
when the value of R is more than 38%, the hard coating has poor
peel resistance and is likely to be abnormally worn. With the
hardness H, the modulus E or the modulus recovery ratio R within
the above range, the entire hard coating has optimally balanced
adhesion strength, lubrication and heat resistance, exhibiting the
maximum effects of the lowermost layer and the uppermost layer,
thereby being effective to prevent abnormal wear.
[0052] The hardness H, the modulus E, and the modulus recovery
ratio R are determined from contact depth measured by a
hardness-measuring method by nano-indentation and the maximum
displacement at the maximum load (W C. Oliver and G. M. Pharr: J.
Mater. Res., Vol. 7, No.6, June, 1992, pp. 1564-1583). The modulus
recovery ratio R is defined as R=100-[(contact depth)/(maximum
displacement at maximum load)]. The hardness H is different from
usual plastic deformation hardness such as Vickers hardness,
etc.
[0053] [2] Coating Method
[0054] The lowermost layer, the intermediate laminate and the
uppermost layer are preferably formed on a substrate by a physical
vapor deposition method. Particularly preferable as the physical
vapor deposition method are a sputtering method and an
arc-discharge ion plating (AIP) method. Using these methods, the
hard coating having excellent hardness, adhesion strength, peel
resistance and abnormal wear resistance can be formed.
[0055] In the above coating method, the lowermost layer, the
intermediate laminate and the uppermost layer are preferably formed
successively, using a lowermost-layer-forming metal target 1 and an
uppermost-layer-forming metal target 2. Specifically, the metal
target 1 is first discharged to form the lowermost layer, and the
metal target 1 and the metal target 2 are then discharged
simultaneously to form the intermediate laminate. Finally, the
discharge of the metal target 1 is stopped, and the uppermost layer
is formed by the metal target 2. By this coating method, the
hard-coated member having excellent seizure resistance and/or wear
resistance can be obtained.
[0056] The hard-coated member of the present invention is
preferably an end mill or a drill having a hard coating formed on a
substrate of high-speed steel, cemented carbide, cermet, etc. The
hard coating remarkably improves the wear resistance, resulting in
a tool with extremely reduced wear. Because the hard coating
particularly improves the lubrication, the hard-coated member is
suitable as a drill.
[0057] The present invention will be explained in more detail
referring to Examples below without intention of restricting the
scope of the present invention.
EXAMPLE 1
[0058] (1) AIP Apparatus
[0059] The formation of a hard coating was conducted using an AIP
apparatus shown in FIG. 2. The AIP apparatus comprises a vacuum
chamber 11, pluralities of arc-discharge evaporators 4-7 disposed
on an inner wall of the vacuum chamber 11, and a substrate holder 8
disposed on a bottom of the vacuum chamber 11. The arc-discharge
evaporators 4-7 are insulated from the wall of the vacuum chamber
11. Each arc-discharge evaporator 4, 6 is provided with a target 1
for forming a metal component of the lowermost layer in the hard
coating, and each arc-discharge evaporator 5, 7 is provided with a
target 2 for forming a metal component of the uppermost layer in
the hard coating. Arc discharge is generated on the targets 1
and/or 2 by supplying predetermined current to each arc-discharge
evaporator 4-7, to evaporate and ionize the metal component, and
metals were vapor-deposited from the targets 1 and/or 2 onto a
substrate 9 placed on the substrate holder 8 by applying a bias
voltage between the vacuum chamber 11 and the substrate holder 8.
The substrate 9 can be rotated at 1-10 rpm by a rotation mechanism
(not shown) mounted to the substrate holder 8. When the substrate 9
faces the target 1, a layer containing the metal component of the
target 1 s formed, and when the substrate 9 faces the target 2, a
layer containing the metal component of the target 2 is formed.
[0060] The addition of carbon, oxygen, nitrogen or boron to the
hard coating was conducted by introducing a gas composition
comprising one or more of a CH.sub.4 gas, a C.sub.2H.sub.2 gas, an
O.sub.2 gas, a CO gas, an N.sub.2 gas, an Ar gas, etc. into the
vacuum chamber 11 during a coating step, such that the desired
coating composition was obtained. For instance, a nitride having a
metal composition of the target can be formed by conducting the
coating step while introducing a nitrogen gas.
[0061] (2) Pretreatment of Substrate
[0062] Using a cemented carbide comprising 13.5% by mass of Co, the
balance being WC and inevitable impurities, as a substrate, an
insert of JIS SNGA432 was produced. After degreasing and washing,
the substrate was mounted to the substrate holder 8, and heated at
550.degree. C. for 30 minutes by a heater disposed in the vacuum
chamber 11 to carry out a degassing treatment. An Ar gas introduced
into the vacuum chamber 11 was then ionized by a heating filament
disposed in the vacuum chamber 11, and bias voltage was applied to
the substrate to clean the substrate surface by Ar ions for 30
minutes.
[0063] (3) Production of Sample 1
[0064] Metal targets 1, 2 produced by a powder metallurgy method
were used to form the hard coating of Sample 1. As shown in FIG. 2,
lowermost-layer-forming targets 1, 1 having a composition of
Al.sub.60Cr.sub.37Si.sub.3 (atomic %) were attached to the
arc-discharge evaporators 4 and 6, and uppermost-layer-forming
targets 2, 2 having a composition of Ti.sub.100 were attached to
the arc-discharge evaporators 5 and 7.
[0065] (a) Formation of Lowermost Layer
[0066] With current of 25 V, 100 A supplied to the evaporators 4
and 6 each having the target 1, a lowermost nitride layer of about
200 nm was formed on the substrate surface under the conditions of
a negative-bias voltage of 50 V, a nitrogen-based reaction gas
pressure of 4 Pa, a substrate temperature of 500.degree. C., and a
substrate-rotating speed of 3 rpm. Although the target composition
was Al.sub.60Cr.sub.37Si.sub.3, the vapor-deposited layer had a
metal composition of Al.sub.57Cr.sub.41Si.sub.2.
[0067] (b) Formation of Intermediate Laminate
[0068] As the coating time passed, current (25 V) supplied to the
evaporators 4 and 6 each having the target 1 was changed stepwise
from 100 A to 60 A, while current (20 V) supplied to the
evaporators 5 and 7 each having the target 2 was changed stepwise
from 60 A to 100 A. Applied to the substrate was a pulse bias
voltage (negative-bias voltage: 60 V, positive bias voltage: 10 V,
frequency: 20 kHz, and amplitude; 80% on the negative side and 20%
the positive side). The nitrogen-based reaction gas pressure was 6
Pa, the substrate temperature was 525.degree. C., and the rotation
speed of the substrate was 6 rpm. Thus, an intermediate nitride
laminate of about 2600 nm was formed on the lowermost layer.
[0069] (c) Formation of Uppermost Layer
[0070] The supply of current to the evaporators 4 and 6 each having
the target 1 was stopped, and an uppermost carbonitride layer of
about 200 nm was formed by the target 2, under the conditions of a
negative-bias voltage of 100 V, a positive bias voltage of 0 V, a
frequency of 10 kHz, an amplitude of 95% on the negative side and
5% on the positive side, a reaction gas pressure of 1.5 Pa
(N.sub.2: 100 sccm, Ar: 30 sccm, C.sub.2H.sub.2: 20 sccm), a
substrate temperature of 500.degree. C., and a substrate-rotating
speed of 3 rpm (Sample 1) .
[0071] (4) Structural Analysis of Sample 1
[0072] The thickness, laminate structure, composition and crystal
structure of the intermediate laminate in the hard coating of
Sample 1 were measured by the following methods. The qualitative
analysis of the crystal structure by X-ray diffraction was
conducted on a hard coating composed only of an intermediate
laminate to remove the influence of the lowermost layer and the
uppermost layer. Using an X-ray diffraction apparatus (Rotaflex
RV-200B, available from Rigaku Corporation) with CuK.alpha. rays as
an X-ray source, the X-ray diffraction measurement was conducted at
a tube voltage of 120 kV and current of 40 .mu.A, an incident angle
of5.degree., an incident slit of 0.4 mm, and 2.theta. of
30.degree.-70.degree.. An X-ray diffraction chart is shown in FIG.
3. FIG. 3 indicates that the intermediate laminate of Sample 1 had
an Fcc structure with at least two peaks in X-ray diffraction in a
2.theta. range of 40.degree. to 45.degree.. In FIG. 3, a peak 1 is
a diffraction peak of (111) planes of the fcc structure of the
layers B, a peak 2 is a diffraction peak of (111) planes of the
layers A, a peak 3 is a diffraction peak of (200) planes of the
layers B, and a peak 4 is a diffraction peak of (200) planes of the
layers A. Diffraction peaks of the substrate are indicated as
"substrate."
[0073] The analysis of the layer structure of the hard coating was
conducted by a transmission electron microscope (TEM). A sample
used in TEM observation was produced by bonding Sample 1 to a dummy
substrate with an epoxy resin, cutting it, bonding a reinforcing
ring to it, grinding and dimpling it, and milling it with Ar ion.
In a region in which Sample 1 was as thick as an atom layer,
structural observation, lattice image observation, micro-area (1 nm
.phi.) energy-dispersive X-ray spectroscopic (EDS) analysis, and
micro-area (1 nm .phi.) electron beam diffraction measurement were
conducted to determine the layer structure of the hard coating.
Using a field emission transmission electron microscope (JEM-2010F,
available from JEOL Ltd.), the structural observation was conducted
at an acceleration voltage of 200 kV. Using a UTW Si (Li)
semiconductor detector attached to the apparatus available from
Noran Instrument, the micro-area EDS analysis was conducted. Thus,
the composition of the laminate was determined on the nanometer
order. Because of using an electron probe having a half-width of 1
nm, the micro-area EDS analysis was able to determine the
composition quantitatively at a thickness of 2 nm or more. The
measurement accuracy was substantially within 2%.
[0074] The identification of the crystal structure of the laminate
was conducted by the micro-area electron beam diffraction at a
camera length of 50 cm and a beam diameter of 1 nm. The cross
section of the intermediate laminate of Sample 1 was observed by a
scanning transmission electron microscope (STEM). The results are
shown in FIG. 4. The intermediate laminate of Sample 1 had a
laminate structure on the nanometer order, each layer being as
thick as about 0.5-100 nm.
[0075] In the intermediate laminate of FIG. 4, a selected-area
diffraction image of 1250 nm.phi. is shown in FIG. 5. The
intermediate laminate of Sample 1 had rings due to two types of
lattice constants, like X-ray diffraction results. The fact that
inner and outer strength distributions were the same in each ring
indicates that crystal particles were aligned, and that the lattice
was continuous in a thickness direction. FIG. 6 is an enlarged view
of FIG. 4. The EDS composition analysis results at positions 1-5
are shown in Table 1. TABLE-US-00001 TABLE 1 Analysis Position
Composition (atomic %) Type of in FIG. 6 Al Si Ti Cr Layer 1 62.65
3.25 4.46 29.61 Layer A 2 6.21 1.52 86.09 6.18 Layer B 3 61.22 2.00
2.68 33.30 Layer A 4 1.58 1.59 94.93 1.09 Layer B 5 0.93 2.51 95.43
1.14 Layer B
[0076] It is clear that the positions 1 and 3 in FIG. 6 are on the
same layer, and that the positions 2, 4 and 5 are also on the same
layer. Table 1 indicates that the Al content (atomic %) of Sample 1
was 61.22-62.65% in the layers A, and 0.93-6.21% in the layers B,
per 100% ofthe metal component. Because vapor deposition is
conducted while rotating the substrate, it may be presumed that a
nitride of Al.sub.60Cr.sub.37Si.sub.3 is formed when the
Al.sub.60Cr.sub.37Si.sub.3 target is close to the substrate, and
that a nitride of Ti.sub.100 is formed when the Ti.sub.100 target
is close to the substrate. However, a mixed layer of an
Al.sub.60Cr.sub.37Si.sub.3 target component and a Ti.sub.100 target
component was actually formed. This appears to be due to the fact
that when coating layers as thick as several nanometers were
laminated, metal components were mutually diffused between them. It
is considered that this mutual diffusion enhances the layer-bonding
strength, providing the hard coating with excellent wear
resistance.
[0077] (5) Production of Samples 2-38
[0078] Samples 2-38 were produced in the same manner as in Sample 1
except for using various targets shown in Table 2. Samples 2-23 are
Examples, Samples 24-28 are Comparative Examples, and Samples 29-38
are Conventional Examples. The hard coating of each Sample was
evaluated as above. The results are shown in Table 3.
[0079] Table 2 shows the compositions of targets mounted to the
evaporators 4-7. With respect to each Sample, Table 3 shows (a) the
composition and thickness of the lowermost layer, (b) the
compositions of layers A and B, the compositions of other layers,
if any, the thickness of each layer, the presence or absence of
mutual diffusion, lattice continuity, the number of peaks in a 20
range of 40.degree.-45.degree., total thickness, hardness, a
modulus, and a modulus recovery ratio in the intermediate laminate,
and (c) the composition and thickness of the uppermost layer. The
composition of each layer in the intermediate laminate was
determined by TEM-EDS in the same manner as in Sample 1. The
thickness was determined from the sectional STEM image. The
hardness, modulus and modulus recovery ratio of the intermediate
laminate were obtained by averaging 10 values measured on the cross
section (mirror-ground in a direction of 5.degree.) of each Sample
by nano-indentation under the conditions of a pushing load of 49 mN
and a maximum load-holding time of 1 second. TABLE-US-00002 TABLE 2
Sample Target Composition (atomic %) Number Targets 4, 6 Target 5
Target 7 1 Al60--Cr37--Si3 Ti Ti 2 Al70--Cr30 Ti Ti 3
Al60--Cr37--Si3 Ti Ti 4 Al60--Cr37--Si3 Ti75--Si25 Ti75--Si25 5
Al60--Cr37--Si3 Ti Ti75--Si25 6 Al60--Cr37--Si3 Ti MoS2 7
Al60--Cr37--Si3 Ti Ti 8 Al55--Cr37--Si3 Ti95--B5 Ti 9
Al60--Cr37--Si3 Ti95--B5 Ti95--B5 10 Al50--Cr47--Si3 Ti Ti 11
Al60--Cr37--Si3 Ti Ti 12 Al60--Cr37--Si3 Ti Ti80--Si20 13
Al60--Cr37--Si3 Ti75--Si25 Ti75--Si25 14 Al60--Cr37--Si3 Ti Ti 15
Al60--Cr37--Si3 Ti Ti 16 Al40--Cr60 Ti Ti 17 Al40--Cr60 Ti Ti 18
Al40--Cr60 Ti Ti 19 Al60--Cr37--Si3 Ti Ti 20 Al60--Cr37--Si3 Ti Ti
21 Al60--Cr37--Si3 Ti45--Al55 Ti75--Si25 22 Al60--Cr37--Si3
Ti50--Al50 Ti75--Si25 23 Al60--Cr37--Si3 Ti75--Al25 Ti75--Si25
24.sup.(1) Al40--Cr30--Si30 Ti Ti 25.sup.(1) Al60--Cr37--Si3 Ti Ti
26.sup.(1) Al20--Cr77--Si3 Ti80--Al20 Ti80--Al20 27.sup.(1)
Al60--Cr37--Si3 Zr75--Si25 Zr75--Si25 28.sup.(1) Al60--Cr37--Si3 Ti
Ti 29.sup.(2) Ti Ti50--Al50 Ti50--Al50 30.sup.(2) Ti50--Al50 -- --
31.sup.(2) Al60--Cr35--Si5 -- -- 32.sup.(2) Al60--Cr40 -- --
33.sup.(2) Al70--Cr30 -- -- 34.sup.(2) Al70--Cr20--Ti10 -- --
35.sup.(2) Al60--Cr25--Ti10--Si5 -- -- 36.sup.(2) Al90--Cr10
Cr90--Al10 Cr90--Al10 37.sup.(2) Al50--Cr50 Ti50--Al50 Ti50--Al50
38.sup.(2) Ti90--Al10 Al90--Ti10 Al90--Ti10 Note:
.sup.(1)Comparative Example .sup.(2)Conventional Example
[0080] TABLE-US-00003 TABLE 3 Sample Lowermost Layer Number
Composition (atomic %) Thickness (nm) 1 (Al57--Cr41--Si2)N 200 2
(Al66--Cr34)N 200 3 (Al57--Cr41--Si2)N 200 4 (Al55--Cr43--Si2)N 200
5 (Al57--Cr41--Si2)N 200 6 (Al57--Cr41--Si2)N 200 7
(Al57--Cr41--Si2)N 200 8 (Al57--Cr41--Si2)N 200 9
(Al57--Cr41--Si2)N 200 10 (Al47--Cr51--Si2)N 200 11
(Al57--Cr41--Si2)N 200 12 (Al57--Cr41--Si2)N 200 13
(Al57--Cr41--Si2)N 200 14 (Al57--Cr41--Si2)N 200 15
(Al57--Cr41--Si2)N 1500 16 (Al36--Cr64)N 200 17 (Al36--Cr64)N 200
18 (Al36--Cr64)N 200 19 (Al57--Cr41--Si2)N 200 20
(Al57--Cr41--Si2)N 200 21 (Al52--Ti48)N 1000 22 (Ti52--Al48)N 1000
23 (Ti78--Al22)N 1000 24.sup.(1) (Al36--Cr40--Si24)N 200 25.sup.(1)
(Al57--Cr41--Si2)N 200 26.sup.(1) (Al17--Cr82--Si1)N 200 27.sup.(1)
(Al57--Cr41--Si2)N 200 28.sup.(1) (Al57--Cr41--Si2)N 200 29.sup.(2)
(Ti)N 500 30.sup.(2) (Ti53--Al47)N -- 31.sup.(2)
(Al56--Cr42--Si2)(N98--O2) -- 32.sup.(2) (Al56--Cr44)(N98--O2) --
33.sup.(2) (Al66--Cr34)N -- 34.sup.(2) (Al66--Cr23--Ti10)N --
35.sup.(2) (Al58--Cr25--Ti15--Si2)N -- 36.sup.(2) -- -- 37.sup.(2)
-- -- 38.sup.(2) -- -- Intermediate Laminate Sample Thickness of
Number Layer A (atomic %) Layer B (atomic %) Each Layer (nm) 1
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 2
(Al6--Cr33--Ti4)N (Al6--Cr4--Ti90)N 10-40 3 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 0.5-10 4 (Al53--Cr37--Ti6--Si4)N
(Al6--Cr5--Ti72--Si17)N 10-40 5 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 6 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 7 (Al63--Cr30--Ti4--Si3)NO
(Al6--Cr6--Ti86--Si2)NO 10-40 8 (Al63--Cr30--Ti4--Si3)NB
(Al6--Cr6--Ti86--Si2)NB 10-40 9 (Al63--Cr30--Ti4--Si3)NB
(Al6--Cr6--Ti86--Si2)NB 10-40 10 (A53--Cr40--Ti4--Si3)N
(Al6--Cr8--Ti86--Si2)N 10-40 11 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 12 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 13 (Al53--Cr37--Ti6--Si4)N.sup.(3)
(Al6--Cr5--Ti72--Si17)N.sup.(3) 10-40 14 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 15 (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 16 (Al43--Cr50--Ti7)N
(Al3--Cr9--Ti91)N 10-40 17 (Al38--Cr55--Ti7)N (Al2--Cr3--Ti95)N
10-40 18 (Al38--Cr55--Ti7)N (Al3--Cr2--Ti95)N 10-40 19
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 20
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 21
(Al59--Cr28--Ti12--Si1)N (Al54--Cr13--Ti32--Si1)N 10-40 22
(Al57--Cr28--Ti14--Si1)N (Al52--Cr8--Ti38--Si1)N 10-40 23
(Al51--Cr27--Ti21--Si1)N (Al31--Cr6--Ti62--Si1)N 10-40 24.sup.(1)
(Al35--Cr35--Ti10--Si20)N (Al6--Cr5--Ti82--Si7)N 10-40 25.sup.(1)
(Al57--Cr41--Si2)N TiN 105-150 26.sup.(1) (Al15--Cr80--Ti4--Si1)N
(Al6--Cr22--Ti70--Si2)N 10-40 27.sup.(1) (Al57--Cr35--Zr5--Si3)N
(A38--Cr12--Zr48--Si2)N 10-40 28.sup.(1) (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 29.sup.(2) (Ti53--Al47)N -- --
30.sup.(2) -- -- -- 31.sup.(2) -- -- -- 32.sup.(2) -- -- --
33.sup.(2) -- -- -- 34.sup.(2) -- -- -- 35.sup.(2) -- -- --
36.sup.(2) (Cr95--Al5)N (A85--Cr15)N 10-40 37.sup.(2) (Ti53--Al47)N
(Cr55--Al45)N 10-40 38.sup.(2) (Ti95--Al5)N (Al85--Ti15)N 10-40
Intermediate Laminate Number of Sample Mutual Lattice Peaks in
Total Thickness Hardness Number Diffusion Continuity
40.degree.-45.degree. (nm) (GPa) 1 Yes Yes 2 2600 36 2 Yes Yes 2
2600 33 3 Yes Yes 2 2600 39 4 Yes Yes 2 2600 36 5 Yes Yes 2 2600 36
6 Yes Yes 2 2600 36 7 Yes Yes 2 2600 38 8 Yes Yes 2 2600 39 9 Yes
Yes 2 2600 39 10 Yes Yes 2 2600 32 11 Yes Yes 2 2600 36 12 Yes Yes
2 2600 36 13 Yes Yes 2 2600 36 14 Yes Yes 2 1300 36 15 Yes Yes 2
1000 36 16 Yes Yes 2 2600 28 17 Yes Yes 2 2600 30 18 Yes Yes 2 2600
30 19 Yes Yes 2 2600 36 20 Yes Yes 2 2600 36 21 Yes Yes 2 1000 36
22 Yes Yes 2 1000 36 23 Yes Yes 2 1000 32 24.sup.(1) Yes Yes 2 2600
26 25.sup.(1) No No 2 2600 26 26.sup.(1) Yes Yes 1 2600 26
27.sup.(1) Yes Yes 2 2600 29 28.sup.(1) Yes Yes 2 2600 36
29.sup.(2) -- -- -- 2500 -- 30.sup.(2) -- -- -- 3000 -- 31.sup.(2)
-- -- -- 3000 -- 32.sup.(2) -- -- -- 3000 -- 33.sup.(2) -- -- --
3000 -- 34.sup.(2) -- -- -- 3000 -- 35.sup.(2) -- -- -- 3000 --
36.sup.(2) No -- -- 3000 -- 37.sup.(2) No -- -- 3000 -- 38.sup.(2)
No -- -- 3000 -- Intermediate Laminate Modulus Uppermost Layer
Sample Modulus Recovery Composition Thickness Number (GPa) Ratio
(%) (atomic %) (nm) 1 490 32 Ti(CN) 200 2 500 30 Ti(CN) 200 3 470
34 Ti(CN) 200 4 490 32 (Ti78--Si22)N 200 5 490 32 (Ti78--Si22)N 200
6 490 32 Ti(CN)/MoS.sub.2 200.sup.(4) 7 470 34 Ti(CN) 200 8 490 34
Ti(CN) 200 9 500 32 Ti(CNB) 200 10 500 31 Ti(CN) 200 11 490 32 TiN
200 12 490 32 (Ti84--Si16)N 200 13 490 32 (Ti78--Si22)N 200 14 490
32 Ti(CN) 1500 15 490 32 Ti(CN) 500 16 510 28 Ti(CN) 200 17 560 28
Ti(CN) 200 18 520 27 Ti(CN) 200 19 490 32 Ti(CNO) 200.sup.(5)
20.sup.(6) 490 32 Ti(CN) 200 21.sup.(7) 480 34 (Ti84--Si16)N 1000
22.sup.(7) 470 34 (Ti84--Si16)N 1000 23.sup.(7) 510 32
(Ti84--Si16)N 1000 24.sup.(1) 460 35 Ti(CN) 200 25.sup.(1) 540 27
Ti(CN) 200 26.sup.(1) 510 29 Ti(CN) 200 27.sup.(1) 530 28
(Zr78--Si22)N 200 28.sup.(1) 490 32 -- -- 29.sup.(2) -- -- -- --
30.sup.(2) -- -- -- -- 31.sup.(2) -- -- -- -- 32.sup.(2) -- -- --
-- 33.sup.(2) -- -- -- -- 34.sup.(2) -- -- -- -- 35.sup.(2) -- --
-- -- 36.sup.(2) -- -- -- -- 37.sup.(2) -- -- -- -- 38.sup.(2) --
-- -- -- Note: .sup.(1)Comparative Example .sup.(2)Conventional
Example .sup.(3)The intermediate laminate had an Si content
changing in a thickness direction. .sup.(4)A 50-nm-thick Ti(CN)
layer was laminated on a 150-nm-thick Ti(CN)/MoS.sub.2 layer formed
by sputtering and AIP. .sup.(5)There was a high oxygen
concentration on the surface. .sup.(6)The hard coating was formed
by sputtering. .sup.(7)The substrate temperature was changed.
EXAMPLE 2
[0081] A hard coating corresponding to each Sample 1-38 of Example
1 was formed on a substrate of a 6-mm-diameter, high-speed-steel
drill (cutting evaluation 1), and on a substrate of a two-edge
cemented carbide ball end mill (cutting evaluation 2),
respectively, and their cutting performance was evaluated under the
following conditions. The layer-forming conditions of each
Experiment were the same as in Example 1 unless otherwise
particularly described, and the experiment numbers corresponds to
the sample numbers in Example 1. The evaluation results are shown
in Table 4.
(a) Conditions of Cutting Evaluation 1
[0082] Work: SCM440 (HRC 30),
[0083] Rotation speed of tool: 3200 rpm,
[0084] Feed per one rotation: 0.15 mm,
[0085] Cutting depth: 15 mm, unpenetrating hole,
[0086] Cutting method: Using an externally supplied aqueous cutting
liquid, and
[0087] Determination of life: Counting the number of drilled holes
until further drilling became impossible (less than 100 holes were
omitted).
(b) Conditions of cutting evaluation 2
[0088] Work: Martensitic stainless steel (HRC 52),
[0089] Rotation speed of tool: 20,000 rpm,
[0090] Feed of table: 4000 m/minute,
[0091] Cutting depth: 0.4 mm in longitudinal direction and 0.2 mm
in pick feed,
[0092] Cutting method: Dry cutting, and
[0093] Determination of life: Cut length until the maximum wear
became as wide as 0.1 mm (less than 10 m was omitted).
TABLE-US-00004 TABLE 4 Cutting Cutting Evaluation 1 Evaluation 2
Experiment Number of Cutting Layer-Forming Number Drilled Holes
Length (m) Conditions 1 1200 520 Same as Sample 1 2 1000 420 Same
as Sample 2 3 1800 580 Same as Sample 3 4 1400 540 Same as Sample 4
5 2100 750 Same as Sample 5 6 1900 460 Same as Sample 6 7 1800 580
Same as Sample 7 8 1800 570 Same as Sample 8 9 1800 540 Same as
Sample 9 10 1200 420 Same as Sample 10 11 1000 380 Same as Sample
11 12 2200 720 Same as Sample 12 13 1600 840 Same as Sample 13 14
800 340 Same as Sample 14 15 1000 420 Same as Sample 15 16 800 320
Same as Sample 16 17 800 340 Same as Sample 17 18 800 340 Same as
Sample 18 19 1600 580 Same as Sample 19 20 1400 620 Same as Sample
20 21 2400 640 Same as Sample 21 22 2300 560 Same as Sample 22 23
1900 550 Same as Sample 23 24.sup.(1) 500 100 Same as Sample 24
25.sup.(1) 400 80 Same as Sample 25 26.sup.(1) 300 80 Same as
Sample 26 27.sup.(1) <100 50 Same as Sample 27 28.sup.(1)
<100 50 Same as Sample 28 29.sup.(2) 300 50 Same as Sample 29
30.sup.(2) 200 30 Same as Sample 30 31.sup.(2) <100 80 Same as
Sample 31 32.sup.(2) <100 50 Same as Sample 32 33.sup.(2)
<100 70 Same as Sample 33 34.sup.(2) 300 70 Same as Sample 34
35.sup.(2) 300 90 Same as Sample 35 36.sup.(2) <100 30 Same as
Sample 36 37.sup.(2) 100 30 Same as Sample 37 38.sup.(2) 200 50
Same as Sample 38 Note: .sup.(1)Comparative Example.
.sup.(2)Conventional Example.
[0094] As shown in Table 4, the comparison of the cutting tools of
Experiments 1 and 2 (each having a hard coating formed under the
layer-forming conditions of Samples 1 and 2) revealed that Sample 1
produced by using an AlCrSi target and a Ti target had a longer
cutting life and thus better wear resistance than those of Sample 2
produced by using an AlCr target and a Ti target. Although the
cutting tool of Experiment 3 had the same composition as that of
Experiment 1, the former had a high-hardness intermediate laminate
because each layer in the intermediate laminate was as thin as
0.5-10 nm, resulting in excellent cutting life. The cutting tool of
Experiment 4 produced by using an AlCrSi target and a TiSi target
had a longer cutting life than that of Experiment 1. The cutting
tool of Experiment 5 having an intermediate laminate formed by an
AlCrSi target and a Ti target, and an uppermost layer formed by a
TiSi target, had excellent wear resistance.
[0095] The cutting tool of Experiment 6 had a 50-nm-thick uppermost
layer of Ti(CN) formed on a laminate (thickness 150 nm) of Ti(CN)
layers and MoS.sub.2 layers each having a nanometer-order
thickness, which were formed by simultaneously operating a
sputtering evaporator and an AIP evaporator. The cutting tool of
Experiment 6 was particularly suitable for drilling. The cutting
tool of Experiment 7 containing oxygen in an intermediate laminate
had excellent wear resistance. This appears to be due to the fact
that oxygen effectively functioned to improve the hardness of the
intermediate laminate and the adhesion of the layers. The cutting
tool of Experiment 8 containing boron in an intermediate laminate
had an excellent cutting life particularly because the intermediate
laminate was hardened. The cutting tool of Experiment 9 containing
boron in an intermediate laminate and an uppermost layer had
excellent chip dischargeability and cutting life. The cutting tool
of Experiment 10 produced by using an AlCrSi target, whose Al
content was different from that of the cutting tool of Experiment
1, had excellent wear resistance like Experiment 1.
[0096] The cutting tool of Experiment 11 having an uppermost layer
made of titanium nitride had a shorter cutting life than that of
Experiment 1. The cutting tool of Experiment 12 having an uppermost
layer of (TiSi)N had particularly excellent wear resistance. The
cutting tool of Experiment 13 with an Si content gradient higher
toward the upper surface in an intermediate laminate had a longer
cutting life and thus better wear resistance than those of the
cutting tool of Experiment 4, which had the same average
composition without gradient. The cutting tools of Experiments 14
and 15 had the same thickness ratio of the lowermost layer, the
intermediate laminate and the uppermost layer as that of Experiment
1.
[0097] The intermediate laminate of the cutting tool of Experiment
16 had hardness of 28 GPa, the intermediate laminate of the cutting
tool of Experiment 17 had a modulus of 560 GPa, and the
intermediate laminate of the cutting tool of Experiment 18 had a
modulus recovery ratio of 27%. These hardness, moduli and modulus
recovery ratios were outside the preferred ranges of the present
invention, resulting in shorter cutting lives than those of the
other cutting tools. The cutting tool of Experiment 19 having the
highest oxygen concentration in a range of 100 nm or less from the
hard coating surface had excellent lubrication. The cutting tool of
Experiment 20 having a hard coating formed by sputtering exhibited
an excellent cutting life like the cutting tools having hard
coatings formed by AIP.
[0098] Samples 21-23 were produced by controlling the Ti content in
the layers B of the intermediate laminate and the substrate
temperature. Specifically, using an AIP method, Samples 21-23 were
produced by forming a 1-.mu.m-thick lowermost layer of (TiAl)N by
the evaporator 5 under the conditions of a bias voltage of 50 V, a
reaction gas pressure of 5 Pa, a substrate temperature of
500.degree. C., and a substrate-rotating speed of 2 rpm, then
forming an intermediate laminate by the evaporators 4, 5, 6 under
the conditions of a bias voltage of 75 V, a reaction gas pressure
of 5 Pa, a substrate temperature of 450.degree. C., and a
substrate-rotating speed of 2 rpm, and further forming a
1-.mu.m-thick uppermost layer of (TiSi)N by the evaporator 7 under
the conditions of a bias voltage of 50 V, a reaction gas pressure
of 3 Pa, a substrate temperature of 450.degree. C., and a
substrate-rotating speed of 2 rpm. The cutting tools of Experiments
21-23 corresponding to these Samples exhibited excellent wear
resistance with little peeling of hard coatings not only in dry
cutting but also in wet or mist cutting.
[0099] The coating conditions of Comparative Examples (cutting
tools of Experiments 24-28) were the same as in Experiment 1,
except for partially changing the layer-forming conditions so as to
provide the properties, structures, etc. shown in Table 2, using
the targets 4-7 having the compositions shown in Table 2. The
cutting tool of Experiment 24 had insufficient adhesion strength
between the intermediate laminate and the uppermost layer and thus
insufficiently improved wear resistance, because the total amount
of Al and Cr in the layers A of the intermediate laminate was 70%.
The cutting tool of Experiment 25 did not have improved wear
resistance, because each layer in the intermediate laminate was as
thick as 105-150 nm, because the uppermost layer and the
intermediate laminate were not sufficiently hardened, and because
there was no mutual diffusion between layers in the intermediate
laminate. The cutting tool of Experiment 26 did not have improved
wear resistance, because the Al content of the intermediate
laminate was 15% or less, and because there was only one peak in
X-ray diffraction in a 20 range of 40.degree. to 45.degree.. The
cutting tool of Experiment 27 having an uppermost layer containing
no Ti, and the cutting tool of Experiment 28 having no uppermost
layer exhibited largely varying and insufficient wear
resistance.
[0100] Sample 29 had a (TiAl)N layer on a lowermost TiN layer.
Sample 30 had a single (TiAl)N layer. Sample 31 had a single
(AlCrSi)N layer. Samples 32 and 33 had a single (AlCr)N layer.
Sample 34 had a single (AlCrTi)N layer. Sample 35 had a single
(AlCrTiSi)N layer. Sample 36 had a (AlCr)N laminate. Sample 37 had
a laminate of (AlCr)N and (TiAl)N. Sample 38 had a (TiAl)N
laminate. The cutting tools (Experiments 29-38) produced under the
same coating conditions as in Samples 29-38 suffered abnormal wear
during the cutting process, resulting in insufficient wear
resistance.
EXAMPLE 3
[0101] (1) Production of Sample 41
[0102] Targets used for forming the layers of Sample 41 were metal
targets produced by a powder metallurgy method. As shown in FIG. 7,
a target 1 of Al.sub.60Cr.sub.37Si.sub.3 (atomic %) was attached to
each arc-discharge evaporator 4, 6, a target 2 of Ti.sub.100 was
attached to the arc-discharge evaporator 5, and a target 3 of
Cr.sub.90Si.sub.5B.sub.5 (atomic %) was attached to the arc
evaporator 7.
[0103] (a) Formation of Lowermost Layer
[0104] Supplying current (25 V, 100 A) to the evaporator provided
with the target 1, a lowermost nitride layer of about 200 nm was
formed on a substrate surface under the conditions of a
negative-bias voltage of 100 V, a reaction gas pressure of 4 Pa, a
substrate temperature of 500.degree. C., and a substrate-rotating
speed of 3 rpm. Though the composition of the target 1 was
Al.sub.60Cr.sub.37Si.sub.3, the metal component composition of the
vapor-deposited lowermost layer was Al.sub.57Cr.sub.41Si.sub.2.
[0105] (b) Formation of Intermediate Laminate
[0106] A nitride layer was formed on the lowermost layer, by
supplying current of 25 V, 100 A to the evaporator provided with
the target 1, and supplying current of 20 V, 60 A to the evaporator
provided with the target 2. Further, the current supplied to the
evaporator provided with the target 2 was changed stepwise from 60
A to 100 A, while the current supplied to the evaporator provided
with the target 1 was changed stepwise from 100 A to 60 A as the
coating time passed. A pulse bias voltage (negative-bias voltage:
100 V, positive bias voltage: 10 V, frequency: 20 kHz, and
amplitude; 80% on the negative side and 20% on the positive side)
was applied to the substrate. An intermediate nitride laminate
having a thickness of about 2600 nm was formed by the targets 1 and
2 under the conditions of a total pressure of 6 Pa, a substrate
temperature of 525.degree. C., and a substrate-rotating speed of 5
rpm.
[0107] (c) Formation of Uppermost Layer
[0108] The supply of current to the evaporators each provided with
the target 1, 2 was stopped, and the supply of current to the
evaporator provided with the target 3 was started to form an
uppermost nitride layer of about 200 nm under the conditions of a
negative-bias voltage of 80 V, a positive bias voltage of 0 V, a
frequency of 10 kHz, an amplitude of 95% on the negative side and
5% on the positive side, a total pressure of 2.5 Pa, a substrate
temperature of 500.degree. C., and a substrate-rotating speed of 3
rpm.
[0109] (2) Production of Samples 42-71
[0110] Samples 42-71 were produced by forming hard coatings in the
same manner as in Sample 41 except for using various targets shown
in Table 5. Samples 42-65 are Examples, and Samples 66-71 are
Comparative Examples. The evaluation results of the hard coating of
each Sample are shown in Table 6. TABLE-US-00005 TABLE 5 Sample
Target Composition (atomic %) Number Targets 4, 6 Target 5 Target 7
41 Al60--Cr37--Si3 Ti Cr90--Si5--B5 42 Al70--Cr30 Ti Cr90--Si5--B5
43 Al60--Cr37--Si3 Ti Cr90--Si5--B5 44 Al60--Cr37--Si3 Ti75--Si25
Cr90--Si5--B5 45 Al60--Cr37--Si3 Ti Cr 46 Al60--Cr37--Si3 Ti
Cr/MoS2 47 Al60--Cr37--Si3 Ti Cr90--Si5--B5 48 Al55--Cr37--Si3
Ti95--B5 Cr90--Si5--B5 49 Al60--Cr37--Si3 Ti95--B5 Cr 50
Al50--Cr47--Si3 Ti Cr90--Si5--B5 51 Al60--Cr37--Si3 Ti
Cr90--Si5--B5 52 Al60--Cr37--Si3 Ti Cr80--Si20 53 Al60--Cr37--Si3
Ti75--Si25 Cr75--Si25 54 Al60--Cr37--Si3 Ti Cr90--Si5--B5 55
Al60--Cr37--Si3 Ti Cr90--Si5--B5 56 Al40--Cr60 Ti Cr90--Si5--B5 57
Al40--Cr60 Ti Cr90--Si5--B5 58 Al40--Cr60 Ti Cr90--Si5--B5 59
Al60--Cr37--Si3 Ti Cr90--Si5--B5 60 Al60--Cr37--Si3 Ti
Cr90--Si5--B5 61 Al60--Cr37--Si3 Ti Cr90--Si5--B5 62
Al60--Cr37--Si3 Ti Cr90--Si5--B5 63 Al60--Cr37--Si3 Ti45--Al55
Cr90--Si5--B5 64 Al60--Cr37--Si3 Ti50--Al50 Cr90--Si5--B5 65
Al60--Cr37--Si3 Ti75--Al25 Cr90--Si5--B5 66.sup.(1)
Al40--Cr30--Si30 Ti Cr90--Si5--B5 67.sup.(1) Al60--Cr37--Si3 Ti
Cr90--Si5--B5 68.sup.(1) Al20--Cr77--Si3 Ti80--Al20 Cr90--Si5--B5
69.sup.(1) Al60--Cr37--Si3 Zr75--Si25 Zr75--Si25 70.sup.(1)
Al60--Cr37--Si3 Ti -- 71.sup.(1) Al60--Cr37--Si3 Cr Cr Note:
.sup.(1)Comparative Example
[0111] TABLE-US-00006 TABLE 6 Sample Lowermost Layer Number
Composition (atomic %) Thickness (nm) 41 (Al57--Cr41--Si2)N 200 42
(Al66--Cr34)N 200 43 (Al57--Cr41--Si2)N 200 44 (Al55--Cr43--Si2)N
200 45 (Al57--Cr41--Si2)N 200 46 (Al57--Cr41--Si2)N 200 47
(Al57--Cr41--Si2)N 200 48 (Al57--Cr41--Si2)N 200 49
(Al57--Cr41--Si2)N 200 50 (Al47--Cr51--Si2)N 200 51
(Al57--Cr41--Si2)N 200 52 (Al57--Cr41--Si2)N 200 53
(Al57--Cr41--Si2)N 200 54 (Al57--Cr41--Si2)N 200 55
(Al57--Cr41--Si2)N 1500 56 (Al36--Cr64)N 200 57 (Al36--Cr64)N 200
58 (Al36--Cr64)N 200 59 (Al57--Cr41--Si2)N 200 60
(Al57--Cr41--Si2)N 200 61 (Al57--Cr41--Si2)N 200 62
(Al57--Cr41--Si2)N 200 63 (Al52--Ti48)N 200 64 (Ti52--Ti48)N 200 65
(Al55--Cr43--Si2)N 200 66.sup.(1) (Al36--Cr40--Si24)N 200
67.sup.(1) (Al57--Cr41--Si2)N 200 68.sup.(1) (Al17--Cr82--Si1)N 200
69.sup.(1) (Al57--Cr41--Si2)N 200 70.sup.(1) (Al57--Cr41--Si2)N 200
71.sup.(1) (Al57--Cr41--Si2)N 200 Intermediate Laminate Sample
Thickness of Each Number Layer A (atomic %) Layer B (atomic %)
Layer (nm) 41 (Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40
42 (Al63--Cr33--Ti3)N (Al6--Cr4--Ti90)N 10-40 43
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 0.5-10 44
(Al53--Cr37--Ti6--Si4)N (Al6--Cr5--Ti72--Si17)N 10-40 45
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 46
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 47
(Al63--Cr30--Ti4--Si3)NO (Al6--Cr6--Ti86--Si2)NO 10-40 48
(Al63--Cr30--Ti4--Si3)NB (Al6--Cr6--Ti86--Si2)NB 10-40 49
(Al63--Cr30--Ti4--Si3)NB (Al6--Cr6--Ti86--Si2)NB 10-40 50
(A53--Cr40--Ti4--Si3)N (Al4--Cr8--Ti86--Si2)N 10-40 51
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 52
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 53
(Al53--Cr37--Ti6--Si4)N.sup.(3) (Al6--Cr5--Ti72--Si17)N.sup.(3)
10-40 54 (Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 55
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 56
(Al43--Cr50--Ti7)N (Al3--Cr9--Ti91)N 10-40 57 (Al38--Cr55--Ti7)N
(Al2--Cr3--Ti95)N 10-40 58 (Al38--Cr55--Ti7)N (Al3--Cr2--Ti95)N
10-40 59 (Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 60
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 61
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 62
(Al63--Cr30--Ti4--Si3)N (Al6--Cr6--Ti86--Si2)N 10-40 63
(Al59--Cr28--Ti12--Si1)N (Al54--Cr13--Ti32--Si1)N 2-20 64
(Al57--Cr28--Ti14--Si1)N (Al52--Cr8--Ti38--Si1)N 2-20 65
(Al49--Cr37--Ti10--Si4)N (Al9--Cr9--Ti65--S17)N 2-20 66.sup.(1)
(Al35--Cr35--Ti10--Si20)N (Al6--Cr5--Ti82--Si7)N 10-40 67.sup.(1)
(Al57--Cr41--Si2)N TiN 105-150 68.sup.(1) (Al15--Cr80--Ti4--Si1)N
(Al6--Cr22--Ti70--Si2)N 10-40 69.sup.(1) (Al57--Cr35--Zr5--Si3)N
(A38--Cr12--Zr48--Si2)N 10-40 70.sup.(1) (Al63--Cr30--Ti4--Si3)N
(Al6--Cr6--Ti86--Si2)N 10-40 71.sup.(1) (Al53--Cr45--Si2)N
(Al6--Cr92--Si2)N 10-40 Intermediate Laminate Sample Mutual Lattice
Number of Total Thickness Hardness Number Diffusion Continuity
Peaks in 40.degree.-45.degree. (nm) (GPa) 41 Yes Yes 2 2600 36 42
Yes Yes 2 2600 33 43 Yes Yes 2 2600 39 44 Yes Yes 2 2600 36 45 Yes
Yes 2 2600 36 46 Yes Yes 2 2600 36 47 Yes Yes 2 2600 38 48 Yes Yes
2 2600 39 49 Yes Yes 2 2600 39 50 Yes Yes 2 2600 32 51 Yes Yes 2
2600 36 52 Yes Yes 2 2600 36 53 Yes Yes 2 2600 36 54 Yes Yes 2 1300
36 55 Yes Yes 2 1000 36 56 Yes Yes 2 2600 28 57 Yes Yes 2 2600 30
58 Yes Yes 2 2600 30 59 Yes Yes 2 2600 36 60 Yes Yes 2 2600 36 61
Yes Yes 2 2600 36 62 Yes Yes 2 2600 36 63 Yes Yes 2 2300 36 64 Yes
Yes 2 2300 36 65 Yes Yes 2 2300 42 66.sup.(1) Yes Yes 2 2600 26
67.sup.(1) No No 2 2600 26 68.sup.(1) Yes Yes 1 2600 26 69.sup.(1)
Yes Yes 2 2600 29 70.sup.(1) Yes Yes 2 2800 36 71.sup.(1) Yes Yes 2
2600 29 Intermediate Laminate Modulus Uppermost Layer Sample
Modulus Recovery Composition Thickness Number (GPa) Ratio (%)
(atomic %) (nm) 41 490 32 (Cr95--Si2--B3)N 200 42 500 30
(Cr95--Si2--B3)N 200 43 470 34 (Cr95--Si2--B3)N 200 44 490 32
(Cr95--Si2--B3)N 200 45 490 32 CrN 200 46 490 32 CrN/MoS.sub.2
200.sup.(8) 47 470 34 (Cr95--Si2--B3)N 200 48 490 34
(Cr95--Si2--B3)N 200 49 500 32 CrN 200 50 500 31 (Cr95--Si2--B3)N
200 51 490 32 (Cr95--Si2--B3)CN 200 52 490 32 (Cr84--Si16)N 200 53
490 32 (Cr78--Si22)N 200 54 490 32 (Cr95--Si2--B3)N 1500 55 490 32
(Cr95--Si2--B3)N 500 56 510 28 (Cr95--Si2--B3)N 200 57 560 28
(Cr95--Si2--B3)N 200 58 520 27 (Cr95--Si2--B3)N 200 59 490 32
(Cr95--Si2--B3)NO 200.sup.(5) 60 490 32 (Cr95--Si2--B3)N
200.sup.(6) 61.sup.(9) 490 32 (Cr95--Si2--B3)N 200 62.sup.(10) 490
32 (Cr95--Si2--B3)N 200 63.sup.(7) 480 34 (Cr95--Si2--B3)N 500
64.sup.(7) 470 34 (Cr95--Si2--B3)N 500 65.sup.(7) 480 35
(Cr95--Si2--B3)N 500 66.sup.(1) 460 35 (Cr95--Si2--B3)N 200
67.sup.(1) 540 27 (Cr95--Si2--B3)N 200 68.sup.(1) 510 29
(Cr95--Si2--B3)N 200 69.sup.(1) 530 28 (Zr78--Si22)N 200 70.sup.(1)
490 32 -- -- 71.sup.(1) 460 27 CrN 200 Note: .sup.(1)Comparative
Example .sup.(3)The Si content in the intermediate laminate was
changing in a thickness direction. .sup.(5)The oxygen concentration
was high on the surface. .sup.(6)The hard coating was formed by
sputtering. .sup.(7)The substrate temperature was changed.
.sup.(8)A 50-nm-thick CrN layer was laminated on the 150-nm-thick
uppermost layer of CrN/MoS.sub.2 formed by sputtering and AIP.
.sup.(9)A 20-nm-thick DLC layer was formed on the uppermost layer.
.sup.(10)A 20-nm-thick (ArCrSi)NO layer was formed on the uppermost
layer.
[0112] Table 5 shows the compositions of targets attached to the
evaporators 4-7 in the vacuum chamber. Table 6 shows (a) the
composition and thickness of the lowermost layer, (b) the
compositions of layers A and B, the compositions of other layers,
if any, the thickness of each layer, the presence or absence of
mutual diffusion, lattice continuity, the number of peaks in a
2.theta. range of 40.degree.-45.degree., total thickness, hardness,
a modulus, and a modulus recovery ratio in the intermediate
laminate, and (c) the composition and thickness of the uppermost
layer. These properties were measured in the same manner as in
Example 1.
EXAMPLE 4
[0113] Each hard coating of Samples 41-71 of Example 3 was formed
on a cutting tool in the same manner as in Example 2 to evaluate
its cutting performance. The layer-forming conditions in
Experiments were the same as in Example 3 unless otherwise
particularly described, and experiment numbers correspond to the
sample numbers of Example 3. The evaluation results are shown in
Table 7. TABLE-US-00007 TABLE 7 Cutting Cutting Evaluation 1
Evaluation 2 Experiment Number of Drilled Cutting Layer-Forming
Number Holes Length (m) Conditions 41 1100 620 Same as Sample 41 42
900 380 Same as Sample 42 43 1800 680 Same as Sample 43 44 1400 740
Same as Sample 44 45 1000 440 Same as Sample 45 46 1800 460 Same as
Sample 46 47 1300 660 Same as Sample 47 48 1500 680 Same as Sample
48 49 1300 540 Same as Sample 49 50 900 360 Same as Sample 50 51
1800 620 Same as Sample 51 52 1900 690 Same as Sample 52 53 2100
840 Same as Sample 53 54 800 340 Same as Sample 54 55 1000 420 Same
as Sample 55 56 800 320 Same as Sample 56 57 800 340 Same as Sample
57 58 800 340 Same as Sample 58 59 1900 710 Same as Sample 59 60
2200 680 Same as Sample 60 61 1900 680 Same as Sample 61 62 1800
700 Same as Sample 62 63 2100 610 Same as Sample 63 64 2400 780
Same as Sample 64 65 2800 890 Same as Sample 65 66.sup.(1) 500 100
Same as Sample 66 67.sup.(1) 400 80 Same as Sample 67 68.sup.(1)
300 80 Same as Sample 68 69.sup.(1) <100 50 Same as Sample 69
70.sup.(1) 200 50 Same as Sample 70 71.sup.(1) 300 50 Same as
Sample 71 .sup.(1)Comparative Example
[0114] As is clear from Table 7, the cutting tools of Experiments
41 and 42 had improved lubrication and seizure resistance, and thus
excellent wear resistance. The cutting tool of Experiment 41
produced by using an AlCrSi target and a Ti target had a longer
cutting life than that of the cutting tool of Experiment 42
produced by using an AlCr target and a Ti target. The cutting tool
of Experiment 43 had high hardness in the intermediate laminate,
and thus excellent cutting life despite the same composition as
that of the cutting tool of Experiment 41, because each layer was
as thin as 0.5-10 nm in the intermediate laminate. The cutting tool
of Experiment 44 produced by using an AlCrSi target and a TiSi
target exhibited a longer cutting life than that of the cutting
tool of Experiment 41. The cutting tool of Experiment 45 had
excellent seizure resistance and wear resistance, because the
intermediate laminate was formed by an AlCrSi target and a Ti
target, and because the uppermost layer was formed by a Cr
target.
[0115] The cutting tool of Experiment 46, in which a 200-nm-thick
laminate of CrN layers and MoS.sub.2 layers having nanometer-level
thickness was formed by simultaneously operating a sputtering
evaporator and an AIP evaporator, was particularly suitable for
drilling. The cutting tool of Experiment 47 containing oxygen in
the intermediate laminate had excellent seizure resistance and wear
resistance. This appears to be due to the fact that oxygen is
effective to increase the hardness of the intermediate laminate and
to improve adhesion between layers. The cutting tools of
Experiments 48 and 49 containing boron in their intermediate
laminates had excellent cutting life because the intermediate
laminates were hardened. The cutting tool of Experiment 50 had
excellent seizure resistance and wear resistance, although the Al
content of the AlCrSi target was different from that used to
produce the cutting tool of Experiment 41.
[0116] The cutting tool of Experiment 51 having an uppermost layer
of chromium carbonitride had a longer cutting life than that of the
cutting tool of Experiment 41 containing no carbon in its uppermost
layer. The cutting tool of Experiment 52 having an uppermost
(CrSi)N layer were excellent particularly in seizure resistance and
wear resistance. The cutting tool of Experiment 43 having an Si
content gradually increasing toward the surface in the thickness
direction of an intermediate laminate had a longer cutting life and
better wear resistance than those of the cutting tool of Experiment
44 having no composition gradient with the same average
composition. The cutting tools of Experiments 54 and 55 had
different thickness ratios of the lowermost layer, the intermediate
laminate and the uppermost layer from that of the cutting tool of
Experiment 41. The thicker intermediate laminate as in the cutting
tool of Experiment 41 provided better results.
[0117] The cutting tool of Experiment 56 comprised an intermediate
laminate having hardness of 28 GPa, the cutting tool of Experiment
57 comprised an intermediate laminate having a modulus of 560 GPa,
and the cutting tool of Experiment 58 had a modulus recovery ratio
of 27%. With these hardness, modulus and modulus recovery ratio
outside the preferred range of the present invention, the cutting
tools of Experiments 56-58 had short cutting lives. The cutting
tool of Experiment 59 having the maximum oxygen concentration in a
range of 100 nm or less from the coating surface was particularly
excellent in lubrication and seizure resistance. The cutting tool
of Experiment 60 having a hard coating formed by a sputtering
method exhibited an excellent cutting life like those having hard
coatings formed by an AIP method.
[0118] The cutting tool of Experiment 61 had a DLC layer of about
20 nm formed on the uppermost layer by a sputtering method. The
cutting tool of Experiment 62 had an (AlCrSi)(NO) layer of about 20
nm formed on the uppermost layer by a sputtering method. While the
cutting tool of Experiment 41 was grayish, the cutting tools of
Experiments 61 and 62 was blue, indicating that the cutting tools'
color was able to be changed to such an extent not to largely
affect their wear resistance.
[0119] The cutting tools of Experiments 63-65 were produced with
substrate temperatures controlled depending on the Ti content of
the layers B in the intermediate laminate. Using an AIP method, the
cutting tools of Experiments 63 and 64 were produced by first
forming a 200-nm-thick lowermost (TiAl)N layer by the evaporator 5
under the conditions of a bias voltage of 50 V, a reaction gas
pressure of 5 Pa, a substrate temperature of 500.degree. C., and a
substrate-rotating speed of 2 rpm, then a 2300-nm-thick
intermediate laminate by the evaporators 4, 5, 6 under the
conditions of a bias voltage of 75 V, a reaction gas pressure of 5
Pa, a substrate temperature of 450.degree. C., and a
substrate-rotating speed of 8 rpm, and further a 500-nm-thick
uppermost (CrSi)BN layer by the evaporator 7 under the conditions
of a bias voltage of 50 V, a reaction gas pressure of 3 Pa, a
substrate temperature of 450.degree. C., and a substrate-rotating
speed of 2 rpm.
[0120] In Experiment 65, using an AIP method, a 200-nm-thick
lowermost (AlCrSi)N layer was first formed by the evaporators 4, 6
under the conditions of a bias voltage of 50 V, a reaction gas
pressure of 5 Pa, a substrate temperature of 450.degree. C., and a
substrate-rotating speed of 2 rpm, and a 2300-nm-thick intermediate
laminate was then formed by the evaporators 4, 5, 6 under the
conditions of a bias voltage of 50 V, a reaction gas pressure of 5
Pa, a substrate temperature of 450.degree. C., and a
substrate-rotating speed of 8 rpm, and a 500-nm-thick uppermost
(CrSiB)N layer was further formed by the evaporator 7 under the
conditions of a bias voltage of 50 V, a reaction gas pressure of 3
Pa, a substrate temperature of 450.degree. C., and a
substrate-rotating speed of 2 rpm. The cutting tools of Experiments
63-65 exhibited excellent wear resistance with little peeling not
only in dry cutting but also in wet or mist cutting.
[0121] Though the coating conditions of Comparative Examples were
the same as those of Samples, partial modifications were made to
provide the properties, structures, etc. shown in Table 6. The
cutting tool of Comparative Example 66 had insufficient adhesion
strength between the intermediate laminate and the uppermost layer
and thus insufficient wear resistance, because the total amount of
Al and Cr in the layers A was 70%. The cutting tool of Comparative
Example 67 had insufficiently hardened uppermost layer and
intermediate laminate without improved wear resistance, because
each layer in the intermediate laminate was as thick as 105-150 nm,
and because there was no mutual diffusion between layers in the
intermediate laminate.
[0122] The cutting tool of Comparative Example 68 did not have
improved seizure resistance and wear resistance, because the Al
content of the intermediate laminate was 15% or less, and because
there was only one peak in X-ray diffraction in a 2.theta. range of
40.degree. to 45.degree.. The cutting tool of Comparative Example
69 containing no Cr in an uppermost layer, and the cutting tool of
Comparative Example 70 having no uppermost layer had largely
changing seizure resistance and wear resistance. The cutting tool
of Comparative Example 71 having an intermediate laminate formed by
using an AlCrSi target and a Cr target had low hardness in the
intermediate laminate, thus failing to have improved wear
resistance.
EFFECT OF THE INVENTION
[0123] Because the hard-coated member of the present invention has
a hard coating having not only excellent hardness and lubrication
but also excellent seizure resistance and/or wear resistance, it
exhibits excellent wear resistance in high-speed cutting, deep
drilling, etc. Further, because the hard-coated member of the
present invention has high adhesion strength between the laminated
layers, peeling is unlikely to occur between the layers.
Accordingly, the hard-coated member exhibits excellent peel
resistance and chipping resistance, with large resistance to
abnormal wear.
* * * * *